Segment Reporting - Components of Segment Profit for Each Segment (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Revenues:
Rental revenue	$ 139,909		$ 150,225	$ 426,021	$ 434,713
Intercompany rental revenue	0		0	0	0
Observatory revenue	4,419		37,575	24,049	91,039
Lease termination fees	331		2,361	1,575	3,112
Third-party management and other fees	283		304	930	955
Other revenue and fees	1,633		2,408	5,254	6,591
Total revenues	146,575		192,873	457,829	536,410
Operating expenses:
Property operating expenses	33,836		47,894	105,054	131,076
Intercompany rent expense	0		0	0	0
Ground rent expense	2,331		2,331	6,994	6,994
General and administrative expenses	14,517		14,421	48,617	44,445
Observatory expenses	5,931		9,089	18,087	25,024
Real estate taxes	31,196		29,599	90,029	86,098
Impairment charges	2,103		0	6,204	0
Depreciation and amortization	44,733		44,260	143,609	135,179
Total operating expenses	134,647		147,594	418,594	428,816
Total operating income	11,928		45,279	39,235	107,594
Other income (expense):
Interest income	366		2,269	2,529	9,907
Interest expense	(23,360)		(19,426)	(66,906)	(60,712)
Loss on early extinguishment of debt	0		0	(86)	0
IPO litigation expense	(1,165)		0	(1,165)	0
Income (loss) before income taxes	(12,231)		28,122	(26,393)	56,789
Income tax (expense) benefit	(38)		(1,338)	2,794	(1,219)
Net income (loss)	(12,269)		26,784	(23,599)	55,570
Segment assets	4,010,714		3,925,317	4,010,714	3,925,317	$ 3,931,834
Expenditures for segment assets	31,347		61,276	80,251	181,568
Real Estate
Operating expenses:
Impairment charges	2,100	$ 4,100		6,200
Operating Segments | Real Estate
Revenues:
Rental revenue	139,909		150,225	426,021	434,713
Intercompany rental revenue	(2,233)		23,242	13,356	58,754
Lease termination fees	331		2,361	1,575	3,112
Third-party management and other fees	283		304	930	955
Other revenue and fees	1,633		2,408	5,254	6,591
Total revenues	139,923		178,540	447,136	504,125
Operating expenses:
Property operating expenses	33,836		47,894	105,054	131,076
Ground rent expense	2,331		2,331	6,994	6,994
General and administrative expenses	14,517		14,421	48,617	44,445
Real estate taxes	31,196		29,599	90,029	86,098
Impairment charges	2,103			6,204
Depreciation and amortization	44,679		44,253	143,522	135,157
Total operating expenses	128,662		138,498	400,420	403,770
Total operating income	11,261		40,042	46,716	100,355
Other income (expense):
Interest income	360		2,269	2,438	9,907
Interest expense	(23,360)		(19,426)	(66,906)	(60,712)
Loss on early extinguishment of debt	0			(86)
IPO litigation expense	(1,165)			(1,165)
Income (loss) before income taxes	(12,904)		22,885	(19,003)	49,550
Income tax (expense) benefit	(196)		(267)	(692)	(762)
Net income (loss)	(13,100)		22,618	(19,695)	48,788
Segment assets	3,771,476		3,659,592	3,771,476	3,659,592
Expenditures for segment assets	30,831		42,901	77,503	134,865
Operating Segments | Observatory
Revenues:
Intercompany rental revenue	0		0	0	0
Observatory revenue	4,419		37,575	24,049	91,039
Total revenues	4,419		37,575	24,049	91,039
Operating expenses:
Intercompany rent expense	(2,233)		23,242	13,356	58,754
General and administrative expenses	0		0	0	0
Observatory expenses	5,931		9,089	18,087	25,024
Impairment charges	0			0
Depreciation and amortization	54		7	87	22
Total operating expenses	3,752		32,338	31,530	83,800
Total operating income	667		5,237	(7,481)	7,239
Other income (expense):
Interest income	6		0	91	0
Interest expense	0		0	0	0
Loss on early extinguishment of debt	0			0
IPO litigation expense	0			0
Income (loss) before income taxes	673		5,237	(7,390)	7,239
Income tax (expense) benefit	158		(1,071)	3,486	(457)
Net income (loss)	831		4,166	(3,904)	6,782
Segment assets	239,238		265,725	239,238	265,725
Expenditures for segment assets	516		18,375	2,748	46,703
Intersegment Elimination
Revenues:
Intercompany rental revenue	2,233		(23,242)	(13,356)	(58,754)
Total revenues	2,233		(23,242)	(13,356)	(58,754)
Operating expenses:
Intercompany rent expense	2,233		(23,242)	(13,356)	(58,754)
General and administrative expenses	0		0	0	0
Impairment charges	0			0
Depreciation and amortization	0		0	0	0
Total operating expenses	2,233		(23,242)	(13,356)	(58,754)
Total operating income	0		0	0	0
Other income (expense):
Interest income	0		0	0	0
Interest expense	0		0	0	0
Loss on early extinguishment of debt	0			0
IPO litigation expense	0			0
Income (loss) before income taxes	0		0	0	0
Income tax (expense) benefit	0		0	0	0
Net income (loss)	0		0	0	0
Segment assets	0		0	0	0
Expenditures for segment assets	$ 0		$ 0	$ 0	$ 0